1. Field of the Invention
The present invention relates to diagnostics and maintenance of complex systems, especially applicable to vehicle systems, and more particularly to a method and apparatus providing intelligent systems monitoring and maintenance.
2. Description of the Related Art
Complex systems such as industrial facilities, or airborne, terrestrial and marine vehicles, are monitored for maintenance purposes and operated by complex control systems. Such control systems are responsible for the operational health, correct maintenance, and general functions of the vehicle or industrial facility. Examples of control systems that also support maintenance and monitoring are an environmental control system (ECS) located on an aircraft, a central computer that controls a flight, a power generation and management system, etc. Control systems of vehicles and system integration laboratory (SIL) facilities monitor performance of individual functional parts commonly known in the industry as Line Replaceable Components or LRCs. Control systems of vehicles and laboratory facilities also monitor the performance of systems that contain the LRCs. Examples of LRCs are sensors, effectors (e.g. valves, pumps, etc.), filters, controllers, etc.
Existing techniques to monitor and maintain vehicle systems or SIL facilities suffer from a host of technical problems that limit the effectiveness of such techniques. Diagnosing of faults without clearly identifiable causes, also known as ambiguous faults, pose a significant challenge to monitoring and maintenance systems. Examples of ambiguous faults are: complex faults that can be caused by failures of multiple LRCs (e.g., excessive cabin temperature fault); No Fault Found reports; and Can Not Duplicate faults. Existing monitoring and maintenance systems have difficulty in correctly isolating the failed LRC in a complex fault with apparent fault symptoms that can be caused by an improper operation, and/or by failures of multiple LRCs. Faced with such a fault scenario, existing monitoring and maintenance systems will simply report multiple failed LRCs.
No Fault Found reports are another type of ambiguous faults. No Fault Found reports cast a doubt on the reliability of the vehicle's subsystems and lead to maintenance personnel's loss of faith in onboard diagnostic results. Subsystem-level Can Not Duplicate faults are especially troublesome and require an in-depth understanding of the performance of the subsystem and its master system. Can Not Duplicate faults also cast a doubt on the reliability of the vehicle's subsystems. Even when No Fault Found and Can Not Duplicate faults are resolved, it is often difficult to verify during systems operation that the faults were correctly resolved.
Monitoring and maintenance systems also provide interpretation of operational test results of vehicle system or SIL facility. However, the tests performed during system operation can produce highly correlated and complex data that requires a thorough understanding of the system performance in order to decipher anomalies hidden in apparently healthy data.
Personnel maintaining or operating a complex vehicle system or lab facility are often not trained to comprehensively understand the intricacies of the embedded diagnostic logic and system performance data, particularly for a newer system where experience based know-how is not yet present. Such training deficiencies cause delay in resolution of system operational issues and present an opportunity for healthy Line Replaceable Components being wrongly identified as failed and then replaced.
Due to the above drawbacks, existing techniques for monitoring and maintaining complex systems present significant commercial challenges. Incorrect or incomplete resolution of system problems and failures add considerable expense to the life cycle costs (LCC) to maintain and operate aircrafts, ships, and lab facilities. Dollar by the hour for maintenance work is a key metric entering costs to diagnose, solve and repair issues on the airplanes, for example. Currently available technology for monitoring and maintaining aircraft systems increase dollar by the hour amounts due to incidences of incorrect or incomplete servicing of the aircraft.
A few publications have studied techniques for monitoring and maintaining complex vehicle and lab systems. In one such technique, a relational database containing fault models and symptom data is used to maintain and diagnose problems aboard an aircraft. However, the technique relies on a clear correspondence between each fault mode and its functional cause. No Fault Found and Can Not Duplicate reports cannot therefore be addressed effectively enough, as there is no clear information as to what fault model and component might have caused them.
According to another technique, the systems that host failed components are isolated, while individual Line Replaceable Components that caused the faults are not isolated.
A disclosed embodiment of the application addresses these and other issues by utilizing an intelligent systems maintenance/monitor system. The system can eliminate identification errors of failed Line Replaceable Components, provide resolution of No Fault Found and Can Not Duplicate reports, learn new fault modes, and train maintenance and engineering personnel.